# First Stage: Demographics → Pension Size

| Model | Dep Var | N | Countries | R² |
|---|---|---|---|---|
| A1: Z → pension_spending | pension_spending_gdp | 1,170 | 41 | 0.393 |
| A2: age ratios → pension | pension_spending_gdp | 1,170 | 41 | 0.399 |
| A3: OECD Z → pension | pension_spending_gdp | 1,108 | 37 | 0.377 |
| A4: non-OECD Z → pension | pension_spending_gdp | 62 | 4 | 0.904 |

## Key Coefficients

| Model | Variable | Coef | SE | p-value | Sig |
|---|---|---|---|---|---|
| A1: Z → pension_spending | Z_1 | 9.1282 | 15.6776 | 0.5605 |  |
| A1: Z → pension_spending | Z_2 | -1.8242 | 2.1239 | 0.3906 |  |
| A1: Z → pension_spending | Z_3 | 0.0949 | 0.0810 | 0.2415 |  |
| A2: age ratios → pension | old_dep | 29.9934 | 4.9281 | 0.0000 | *** |
| A2: age ratios → pension | youth_dep | -9.7021 | 5.2268 | 0.0637 | * |
| A3: OECD Z → pension | Z_1 | 9.9922 | 15.9373 | 0.5308 |  |
| A3: OECD Z → pension | Z_2 | -1.9653 | 2.1574 | 0.3625 |  |
| A3: OECD Z → pension | Z_3 | 0.0996 | 0.0822 | 0.2258 |  |
| A4: non-OECD Z → pension | Z_1 | -22.3552 | 66.2676 | 0.7371 |  |
| A4: non-OECD Z → pension | Z_2 | 0.8968 | 9.2729 | 0.9233 |  |
| A4: non-OECD Z → pension | Z_3 | 0.0456 | 0.3602 | 0.8998 |  |

*First stage: demographics predict pension system size*